1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) and a driving method thereof. More particularly, the present invention relates to a liquid crystal display (LCD) using an ALS driving method, and a driving method thereof.
2. Description of the Related Art
As a representative display device, a liquid crystal display (LCD) includes two display is panels provided with pixel electrodes and a common electrode, and a liquid crystal layer having dielectric anisotropy interposed between the two panels. The pixel electrodes are arranged in a matrix format and are connected to a switch such as a thin film transistor (TFT) to sequentially receive a data voltage by row. The common electrode is formed over the entire surface of the display panel to receive a common voltage. The pixel electrodes, the common electrode, and the liquid crystal layer interposed between the pixel electrodes and the common electrode form a liquid crystal capacitor from a circuital view, and the liquid crystal capacitor and a switch connected thereto become a basic unit forming a pixel.
In the liquid crystal display (LCD), an electric field is generated in the liquid crystal layer by applying voltages to the two electrodes, and transmittance of light passing through the liquid crystal layer is controlled by controlling the electric field to thereby display a desired image. At this time, in order to prevent a degradation phenomenon caused by long application of an electric field in one direction to a liquid crystal layer, polarity of the data voltage with respect to the common voltage is inverted for respective frames, respective rows, or respective pixels.
The ALS driving method as a driving method for boosting a voltage of a pixel boosts the voltage of a pixel electrode that is floated after a gate voltage is turned off by coupling it with the voltage of an ALS line. The boosting of the voltage of the pixel electrode may be induced by increasing or decreasing the voltage of the boost line during one frame. The ALS driving method may reduce a source output voltage of a driving circuit, thereby reducing power consumption. Also, the ALS driving method may increase the pixel voltage, and the response speed of the liquid crystal may be improved through the application of the high pixel voltage.
However, the boost line accords with the direction of a scan line and overlaps the data line, such that the voltage of the boost line may have noise because of coupling with the data voltage applied to the data line.
For example, when the scan line is applied with a gate-on voltage such that the data line is applied with the data voltage, the noise voltage is generated in the boost line by the coupling with the data line. The noise voltage generated in the boost line must be restored until the gate-off voltage is applied and the boost voltage is applied. If the noise voltage generated in the boost line is not restored until the boost voltage is applied, the output signal of the boost line is changed and output by the noise voltage.
When the gate-off voltage is applied, the deviation of the noise voltage that is not restored in the boost line causes a difference of the pixel voltage, and thereby crosstalk may be generated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.